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V E Fortov - One of the best experts on this subject based on the ideXlab platform.
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Dust Particle radial confinement in a dc glow discharge
Physical Review E, 2013Co-Authors: G I Sukhinin, A V Fedoseev, O F Petrov, S N Antipov, V E FortovAbstract:: A self-consistent nonlocal model of the positive column of a dc glow discharge with Dust Particles is presented. Radial distributions of plasma parameters and the Dust component in an axially homogeneous glow discharge are considered. The model is based on the solution of a nonlocal Boltzmann equation for the electron energy distribution function, drift-diffusion equations for ions, and the Poisson equation for a self-consistent electric field. The radial distribution of Dust Particle density in a Dust cloud was fixed as a given steplike function or was chosen according to an equilibrium Boltzmann distribution. The balance of electron and ion production in argon ionization by an electron impact and their losses on the Dust Particle surface and on the discharge tube walls is taken into account. The interrelation of discharge plasma and the Dust cloud is studied in a self-consistent way, and the radial distributions of the discharge plasma and Dust Particle parameters are obtained. It is shown that the influence of the Dust cloud on the discharge plasma has a nonlocal behavior, e.g., density and charge distributions in the Dust cloud substantially depend on the plasma parameters outside the Dust cloud. As a result of a self-consistent evolution of plasma parameters to equilibrium steady-state conditions, ionization and recombination rates become equal to each other, electron and ion radial fluxes become equal to zero, and the radial component of electric field is expelled from the Dust cloud.
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The corona discharge in nuclear excited plasma as a way of obtaining ordered Dust Particle structures
High Temperature, 2012Co-Authors: O A Sinkevich, V S Filinov, V I Vladimirov, V E Fortov, L. V. Deputativa, V. N. Naumkin, V. I. Meshakin, V. A. RykovAbstract:A model of a corona discharge in a nuclear excited Dust plasma at the pressures of 1–100 atm is proposed. The distributions of the electric field and current-voltage characteristics of a corona discharge in a nuclear-excited Dust plasma are found for a particular cylindrical geometry case at different methods of corona-producing electrode positioning. The conditions for the existence of a stationary corona discharge are obtained. A mathematical model describing the behavior of Dust Particles in a nuclear plasma that allows taking into account the key physical processes occurring in a nuclear-excited Dust plasma is considered. The analyzed plasma properties are as follows: (1) shielding of the Coulomb forces of the interaction between Dust Particles, (2) the energy exchange and the stochastic character of the Dust Particle interaction with a buffer gas and ambient plasma, and (3) strong spatial inhomogeneity of the nuclear-excited plasma. The use of a corona discharge in a nuclear-excited plasma will make it possible to ensure stability of plasma-Dust structures and more efficient conversion of the nuclear energy into laser radiation.
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effect of trapped ions and nonequilibrium electron energy distribution function on Dust Particle charging in gas discharges
Physical Review E, 2009Co-Authors: G I Sukhinin, A V Fedoseev, O F Petrov, S N Antipov, V E FortovAbstract:: Dust-Particles charging in a low-pressure glow discharge was investigated theoretically. The Dust-Particle charge was found on the basis of a developed self-consistent model taking into account the nonequilibrium character of electron distribution function and the formation of an ionic coat composed of bound or trapped ions around the Dust Particle. The Dust-Particle charge, the radial distributions of electron density, free and trapped ions densities, and the distribution of electrostatic potential were found. It was shown that the non-Maxwellian electron distribution function and collisional flux of trapped ions both reduce the Dust-Particle charge in comparison with that received with the help of the conventional orbital motion limited (OML) model. However, in rare collisional regimes in plasma when the collisional flux is negligible, the formation of ionic coat around a Particle leads to a shielding of the proper charge of a Dust Particle. In low-pressure experiments, it is only possible to detect the effective charge of a Dust Particle that is equal to the difference between the proper charge of the Particle and the charge of trapped ions. The calculated effective Dust Particle charge is in fairly good agreement with the experimental measurements of Dust-Particle charge dependence on gas pressure.
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formation and behaviour of Dust Particle clouds in a radio frequency discharge results in the laboratory and under microgravity conditions
New Journal of Physics, 2003Co-Authors: Maxime Mikikian, G.e. Morfill, Laifa Boufendi, A Bouchoule, H M Thomas, Anatoly P Nefedov, V E FortovAbstract:In this paper we report the first observation on submicron Dust Particle clouds grown in a radio-frequency sputtering discharge under microgravity conditions. These results have been obtained in the PKE-Nefedov (Plasma Kristall Experiment) chamber in the framework of a French-German-Russian programme. A Dust-free region, usually called the `void', is observed in the laboratory and under microgravity conditions even with submicron Particles. In this region, successive generations of Particles can be grown, leading to the coexistence of Particles with various sizes. Each generation of Particles constitutes a cloud separated from the others by a definite sheath. Dynamics of these clouds have been investigated showing vortex-like motions or independent behaviour of small heaps of Particles, emphasizing both attractive and repulsive effects between Dust clouds. As these Particles drastically influence the plasma properties, the growth kinetics is followed through the evolution of the discharge current.
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dependence of the Dust Particle charge on its size in a glow discharge plasma
Physical Review Letters, 2001Co-Authors: V E Fortov, A P Nefedov, V I Molotkov, M Y Poustylnik, V M TorchinskyAbstract:Measurements of the charge of Dust grains have been performed in a quasineutral plasma over a wide range of grain sizes. A new method was established for measuring the charge on grains levitating in the striations of a dc glow discharge. A single Dust Particle is moved out of a Dust cloud with the help of a focused laser beam. When it leaves the beam it returns back to the cloud, and the charge on the grain is derived from the analysis of the returning trajectory. The obtained dependence of the Dust-grain charge on its size was found to be strongly nonlinear in the experimental conditions. The problem of the charging of Dust Particles in a plasma is one of the main tasks to be studied. In a plasma Dust Particles acquire a charge (typically it is negative), interact with each other, and their presence may lead to a significant change of the plasma properties. Since the electrostatic energy of interacting Particles strongly exceeds their thermal energy, the Particles can form an ordered lattice. The so-called plasma crystals have been widely studied with respect to lattice formation [1,2], phase transitions [3], and waves and instabilities [4]. The determination of the grain’s charge is very important in all of these experiments in order to reveal whether the Dust system is strongly or weakly coupled [5]. The charge of the Dust grains is of great interest to understand the behavior of particulates in processing plasmas used for thin-film production, in processes of growing Particles in the gas phase by nucleation and aggregation [6] as well as for the study of space plasmas, e.g., interstellar clouds and planetary rings [7]. There is a requirement to obtain reliable experimental data on the value of the Dust-Particle charge over a wide range of grain sizes and plasma parameters. However, no methods for measuring the charge on the Dust Particles were proposed for the direct current (dc) discharge Dusty plasma. For rf discharge plasmas several methods have been developed. In the first method, initiated by [8,9] the charge is derived from a response of a simple ordered system (chain, monolayer, etc.) of Dust Particles on a periodical disturbance. In the second method [10], the charge was determined from the trajectories of the Particles in binary collisions. In the third method [11], Mach cones were excited in a 2D crystal by the fast Dust Particles, and the charge was derived from the analysis of these waves. However, the crucial condition for the application of these methods is low neutral gas pressure (of the order of 10 22 10 21 torr). In this Letter, we present the results of the measurements of the charge on Dust grains in the striations of a dc discharge obtained with a new method. The experiments were carried out in a glass discharge tube [12] of 36 mm diameter and 40 cm interelectrode distance. The glow discharge with cold electrodes was produced in neon in the range of pressures 0.5 1.5 torr. The discharge current varied from 0.4 to 3 mA. In this range of parameters, regimes with standing striations existed. Dust Particles were stored in a container with a grid at the bottom, positioned above the anode. Through the shaking of the container, the Particles were dispersed into the plasma region then levitated in the striations where they formed ordered structures. Melamine-formaldehyde Particles of 1.87, 4.82, and 13.57 mm diameter were used. A 50 mW diode laser was used for the illumination of the Particles. The scattered light was observed by a CCD video camera. The specificity of the striations of a dc glow discharge is such that a stable levitation of Dust Particles occurs at relatively high pressures (0.5 2 torr). At lower pressures self-excited waves are developing in the Dusty plasma structures [4], making the measurement of the charge with the techniques, cited above, impossible.
A Piel - One of the best experts on this subject based on the ideXlab platform.
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exploring the wake of a Dust Particle by a continuously approaching test grain
Physics of Plasmas, 2015Co-Authors: Hendrik Jung, F Greiner, Oguz Han Asnaz, Jan Carstensen, A PielAbstract:The structure of the ion wake behind a Dust Particle in the plasma sheath of an rf discharge is studied in a two-Particle system. The wake formation leads to attractive forces between the negatively charged Dust and can cause a reduction of the charge of a Particle. By evaluating the dynamic response of the Particle system to small external perturbations, these quantities can be measured. Plasma inherent etching processes are used to achieve a continuous mass loss and hence an increasing levitation height of the lower Particle, so that the structure of the wake of the upper Particle, which is nearly unaffected by etching, can be probed. The results show a significant modification of the wake structure in the plasma sheath to one long potential tail.
Ping Yang - One of the best experts on this subject based on the ideXlab platform.
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Dust Particle detection in surveillance video using salient visual descriptors
Computers & Electrical Engineering, 2017Co-Authors: Ping Yang, Li Chen, Jing Tian, Xin XuAbstract:We identify the Dust Particles in images using salient visual descriptors.We exploit localized color, texture and shape saliency features.We develop a machine learning approach to detect Dust Particle in images. Display Omitted Outdoor surveillance video that suffers from dirty camera lenses has the potential for deteriorated performance in many applications, such as vehicle tracking and target recognition. This paper proposes to identify the Dust Particles in images using a set of salient visual descriptors. More specifically, the proposed approach exploits an extended feature descriptor comprising localized color, texture and shape saliency features. These proposed features are further incorporated into a machine learning approach, followed by a Dust Particle localization approach, for detecting Dust Particle in images. The proposed approach is able to achieve superior Dust Particle detection performance to that of conventional approaches, as evaluated in real-world video surveillance scenarios.
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impact of radiatively interactive Dust aerosols in the nasa geos 5 climate model sensitivity to Dust Particle shape and refractive index
Journal of Geophysical Research, 2014Co-Authors: Peter R Colarco, Ping Yang, Edward Paul Nowottnick, C A Randles, Bingqi Yi, Jamison A Smith, Charles D BardeenAbstract:The radiative effects of Saharan Dust aerosols are investigated in the NASA GEOS-5 atmospheric general circulation model. A sectional aerosol microphysics model (CARMA) is run online in GEOS-5. CARMA treats the Dust aerosol lifecycle, and its tracers are radiatively coupled to GEOS-5. A series of AMIP-style simulations are performed, in which input Dust optical properties (Particle shape and refractive index) are varied. Simulated Dust distributions for summertime Saharan Dust compare well to observations, with best results found when the most absorbing Dust optical properties are assumed. Dust absorption leads to a strengthening of the summertime Hadley cell circulation, increased Dust lofting to higher altitudes, and a strengthening of the African easterly jet, resulting in increased Dust atmospheric lifetime and farther northward and westward transport. We find a positive feedback of Dust radiative forcing on emissions, in contrast with previous studies, which we attribute to our having a relatively strong longwave forcing caused by our simulating larger effective Particle sizes. This longwave forcing reduces the magnitude of midday net surface cooling relative to other studies, and leads to a nighttime warming that results in higher nighttime wind speeds and Dust emissions. The radiative effects of Dust Particle shape have only minor impact on transport and emissions, with small (~5%) impact on top of atmosphere shortwave forcing, in line with previous studies, but relatively more pronounced effects on shortwave atmospheric heating and surface forcing (~20% increase in atmospheric forcing for spheroids). Shape effects on longwave heating terms are of order ~10%.
Zh A Moldabekov - One of the best experts on this subject based on the ideXlab platform.
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Charging of a Dust Particle in a Magnetized Gas Discharge Plasma
IEEE Transactions on Plasma Science, 2019Co-Authors: S K Kodanova, T. S. Ramazanov, Kh N Bastykova, S. A. Maiorov, G. N. Nigmetova, Zh A MoldabekovAbstract:The effect of an external magnetic field on the Dust Particle charging in gas discharge plasmas has been studied using the Particle-in-cell and Monte Carlo methods at 1, 2, and 4 T. This paper presents the results for the Dust Particle charge and the characteristic Dust Particle charging time for different values of the magnetic field induction. Our simulations have shown that the external magnetic field reduces the absolute value of the Dust Particle charge and extends the characteristic charging time. In addition, the number density of electrons and ions decreases in the vicinity of the Dust Particle due to the magnetic force, which we interpret as the action of the external magnetic field hampering plasma flow to the surface of the charged Dust Particle. To visualize this effect, we show the trajectories of the electrons and ions around the Dust Particle at different values of the magnetic field induction.
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Scattering of Dust Particles With Nonzero Dipole Moments
IEEE Transactions on Plasma Science, 2016Co-Authors: S K Kodanova, T. S. Ramazanov, Kh N Bastykova, Zh A MoldabekovAbstract:The process of scattering of one Dust Particle on another Dust Particle in complex plasmas is considered. The dipole moments of Dust Particles are taken into account. The results on the scattering angle and scattering cross section are presented, and the interesting effect of zero-angle Dust Particle-Dust Particle scattering is predicted.
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effect of Dust Particle polarization on scattering processes in complex plasmas
Physics of Plasmas, 2015Co-Authors: S K Kodanova, T. S. Ramazanov, Kh N Bastykova, Zh A MoldabekovAbstract:Screened interaction potentials in Dusty plasmas taking into account the polarization of Dust Particles have been obtained. On the basis of screened potentials scattering processes for ion-Dust Particle and Dust Particle-Dust Particle pairs have been studied. In particular, the scattering cross section is considered. The scattering processes for which the Dust grain polarization is unimportant have been found. The effect of zero angle Dust Particle-Dust Particle scattering is predicted.
G I Sukhinin - One of the best experts on this subject based on the ideXlab platform.
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plasma anisotropy around a Dust Particle placed in an external electric field
Physical Review E, 2017Co-Authors: G I Sukhinin, A V Fedoseev, M V Salnikov, A Rostom, M M Vasiliev, O F PetrovAbstract:: A self-consistent model of plasma polarization around an isolated micron-sized Dust Particle under the action of an external electric field is presented. It is shown that the quasineutral condition is fulfilled and the formed volume charge totally screens the Dust Particle. The ion focusing and wake formation behind the Dust Particle are demonstrated for different ion mean free paths and the external electric fields. It is obtained that at low values of the external electric field the trapped ions play the main role in the screening of the Dust Particle charge. For high external electric fields, the density of trapped ions decreases and the Dust Particle is screened mainly by the free ions.
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Dust Particle radial confinement in a dc glow discharge
Physical Review E, 2013Co-Authors: G I Sukhinin, A V Fedoseev, O F Petrov, S N Antipov, V E FortovAbstract:: A self-consistent nonlocal model of the positive column of a dc glow discharge with Dust Particles is presented. Radial distributions of plasma parameters and the Dust component in an axially homogeneous glow discharge are considered. The model is based on the solution of a nonlocal Boltzmann equation for the electron energy distribution function, drift-diffusion equations for ions, and the Poisson equation for a self-consistent electric field. The radial distribution of Dust Particle density in a Dust cloud was fixed as a given steplike function or was chosen according to an equilibrium Boltzmann distribution. The balance of electron and ion production in argon ionization by an electron impact and their losses on the Dust Particle surface and on the discharge tube walls is taken into account. The interrelation of discharge plasma and the Dust cloud is studied in a self-consistent way, and the radial distributions of the discharge plasma and Dust Particle parameters are obtained. It is shown that the influence of the Dust cloud on the discharge plasma has a nonlocal behavior, e.g., density and charge distributions in the Dust cloud substantially depend on the plasma parameters outside the Dust cloud. As a result of a self-consistent evolution of plasma parameters to equilibrium steady-state conditions, ionization and recombination rates become equal to each other, electron and ion radial fluxes become equal to zero, and the radial component of electric field is expelled from the Dust cloud.
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Interaction between glow discharge plasma and Dust Particles
Thermophysics and Aeromechanics, 2011Co-Authors: A V Fedoseev, T. S. Ramazanov, S K Kodanova, G I Sukhinin, N. H. BastykovaAbstract:The effect of Dust Particle concentration on gas discharge plasma parameters was studied through development of a self-consistent kinetic model which is based on solving the Boltzmann equation for the electron distribution function. It was shown that an increase in the Havnes parameter causes an increase in the average electric field and ion density, as well as a decrease in the charge of Dust Particles and electron density in a Dust Particle cloud. Self-consistent simulations for a wide range of plasma and Dust Particle parameters produced several scaling laws: these are laws for Dust Particle potential and electric field as a function of Dust Particle concentration and radius, and the discharge current density. The simulation results demonstrate that the process of self-consistent accommodation of parameters of Dust Particles and plasma in condition of Particle concentration growth causes a growth in the number of high-energy electrons in plasma, but not to depletion of electron distribution function.
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Influence of Dust-Particle concentration on gas-discharge plasma.
Physical review. E Statistical nonlinear and soft matter physics, 2010Co-Authors: G I Sukhinin, A V FedoseevAbstract:A self-consistent kinetic model of a low-pressure dc glow discharge with Dust Particles based on Boltzmann equation for the electron energy distribution function is presented. The ions and electrons production in ionizing processes as well as their recombination on the Dust-Particle surface and on the discharge tube wall were taken into account. The influence of Dust-Particle concentration N(d) on gas discharge and Dust Particles parameters was investigated. It is shown that the increase of N(d) leads to the increase of an averaged electric field and ion density, and to the decrease of a Dust-Particle charge and electron density in the Dusty cloud. The results were obtained in a wide region of different discharge and Dusty plasma parameters: Dust Particles density 10(2)-10(8) cm(-3), discharge current density 10(-1)-10(1) mA/cm(2), and Dust Particles radius 1, 2, and 5 microm. The scaling laws for Dust-Particle surface potential and electric filed dependencies on Dust-Particle density, Particle radius and discharge currents were revealed. It is shown that the absorption of electrons and ions on the Dust Particles surface does not lead to the electron energy distribution function depletion due to a self-consistent adjustment of Dust Particles and discharge parameters.
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Influence of Dust-Particle concentration on gas-discharge plasma.
Physical Review E, 2010Co-Authors: G I Sukhinin, A V FedoseevAbstract:A self-consistent kinetic model of a low-pressure dc glow discharge with Dust Particles based on Boltzmann equation for the electron energy distribution function is presented. The ions and electrons production in ionizing processes as well as their recombination on the Dust-Particle surface and on the discharge tube wall were taken into account. The influence of Dust-Particle concentration N{sub d} on gas discharge and Dust Particles parameters was investigated. It is shown that the increase of N{sub d} leads to the increase of an averaged electric field and ion density, and to the decrease of a Dust-Particle charge and electron density in the Dusty cloud. The results were obtained in a wide region of different discharge and Dusty plasma parameters: Dust Particles density 10{sup 2}-10{sup 8} cm{sup -3}, discharge current density 10{sup -1}-10{sup 1} mA/cm{sup 2}, and Dust Particles radius 1, 2, and 5 mum. The scaling laws for Dust-Particle surface potential and electric filed dependencies on Dust-Particle density, Particle radius and discharge currents were revealed. It is shown that the absorption of electrons and ions on the Dust Particles surface does not lead to the electron energy distribution function depletion due to a self-consistent adjustment of Dust Particles and dischargemore » parameters.« less
